1. Technical Field
The present invention relates to a recording medium determination apparatus and a recording medium determination method, each of which determines the thickness of a recording medium such as paper, for example, onto which an image is recorded.
2. Related Art
In technology in which an image is recorded onto a recording medium such as paper or a resin sheet, there is a case in which it is necessary to determine the thickness of the recording medium which is used, for example, in order to optimize the handling of the recording medium according to the characteristics thereof. As technology which is usable for this purpose, there is technology in which the thickness of the recording medium is measured optically, as disclosed in JP-A-2006-168138 and JP-A-2010-042646, for example.
In the technology disclosed in JP-A-2006-168138, the thickness of the recording medium is obtained from the distance to the recording medium surface by radiating light onto the recording medium, receiving the specular reflection light using a line sensor and detecting the position at which the received light amount is the greatest. In addition, in the technology disclosed in JP-A-2010-042646, the thickness of the recording medium is obtained on the basis of a detected light amount by positioning optical sensors in two locations, the distances between the optical sensors and the recording medium being different from one another, and performing detection of the reflected light.
Both of the technologies of the related art described above are capable of directly detecting the thickness of an arbitrary recording medium using an optical method. However, there is still room for improvement in the detection accuracy. In other words, in the technology disclosed in JP-A-2006-168138, since the thickness of the recording medium is obtained from the peak position of the reflection light intensity, the light concentrating properties of the radiated light influence the detection accuracy. In addition, since a line sensor is necessary for the detection, there is also a problem in that the cost of the apparatus increases. In addition, in the technology disclosed in JP-A-2010-042646, since the detection involves moving the optical sensor, there is a problem in that the positioning accuracy of the optical sensor influences the detection accuracy.